1. Field of the Invention
The present invention relates to a novel organic compound and an organic light-emitting device using the same.
2. Related Background Art
An organic light-emitting device includes an anode, a cathode, and a thin film containing a fluorescent organic compound or a phosphorescent organic compound, which is sandwiched between the anode and the cathode. An electron and a hole are injected from the respective electrodes, whereby an exciton of the fluorescent compound or the phosphorescent compound is generated. The device utilizes light radiated when the exciton returns to its ground state.
The recent progress of an organic light-emitting device is significant, and suggests that the device can be used in wide applications because of making it possible to form a thin, light-weight organic light-emitting device having a high luminance at a low applied voltage, a variety of emission wavelengths, and high-speed responsiveness. However, at present, improvements in initial characteristics such as a luminous efficiency, and duration characteristics such as duration against luminance degradation due to long-term light emission have been needed. Those initial characteristics and duration characteristics result from all layers for forming the device, including a hole injection layer, a hole transport layer, a light emission layer, a hole blocking layer, an electron transport layer, an electron injection layer, and the like.
Examples of conventionally known materials to be used in the hole blocking layer, the electron transport layer, and the electron injection layer include phenanthroline compounds, aluminum quinolinol complexes, oxadiazole compounds, and triazole compounds. For example, in each of Japanese Patent Application Laid-open Nos. H05-331459, H07-082551, 2001-267080, 2001-131174, H02-216791 and H10-233284, and U.S. Pat. Nos. 4,539,507, 4,720,432 and 4,885,211, each of the above materials is used in a light emission layer or an electron transport layer. However, the initial characteristics and duration characteristics of an organic light-emitting device of each of those documents are not sufficient.
An object of the present invention is to provide a novel 1,8-naphthyridine compound.
Another object of the present invention is to provide an organic light-emitting device having a high emission luminance and a high emission efficiency by using the novel 1,8-naphthyridine compound. Another object of the present invention is to provide an organic light-emitting device having high durability and showing small degradation of luminance due to long-term light emission.
Further another object of the present invention is to provide an organic light-emitting device that can be easily produced at a relatively low cost.